The present invention relates to a high-reliability computer system, and specifically to a high-reliability computer system which has excellent durability and excellent resistance to an undesirable environment.
Recently, computer capability has been progressively improved with the increasing number of peripherals. As a result, the consumption of electric power required for operating computers has markedly increased. Additionally, according to downsizing, the size of conventional main bodies and their peripherals have been minimized and a large number of small systems are being concentrated in small areas. This increase in electric power consumption per unit and concentration of units result in increased heat generated. Therefore, forcible coolers are required for power source units and IC boards where these parts are concentrated. As shown in FIG. 1, common personal computers and mini-computers are provided with a cooling fan or an air filter. In FIG. 1, a case 1 is designed to be easily moved on four casters 10 attached to it. Inside the case, various function modules and peripherals are provided. These include a floppy disk drive 2, hard disk drives 3, a power source 4, a plurality of cards (IC board) 5, a mother board 6 for holding the cards and connecting them through buses, a card shelf 7 for storing the mother board 6 and the cards 5, and three fans O and an air filter 9 for cooling the heat generated by these modules and units.
The cards 5 comprise function modules such as a CPU (central processing unit), memories such as ROMs (read only memories) and RAMs (random access memories), an input/output controller, and a communication controller, etc. Normally, a plurality of electrical parts, mainly IC, are arranged on a printed circuit.
To cool the computer system air is first drawn into the case by the three moving fans 8 through the space formed by the four casters 10 between the bottom plate of the case 1 and the floor, and through the air filter 9 where it is purified. Then, the air removes the heat generated at each of the parts and radiates the heat the direction indicated by the arrow A.
With dust-proof FA (factory automation) personal computers, FA computers, etc., a fine filter is utilized to protect the contents of the computer system from dust in air worse and dustier than the normal atmosphere. A more powerful fan must be mounted in order to inhale outside air against the larger air resistance generated by a dust-clogged fine filter.
However, the above described forcible cooling fan normally has poor durability, and must be replaced every two or three years. This is the main reason for a short mean time to failure (MTBF) of computer systems. In an undesirable atmosphere, air filters become filled with dust very quickly, and maintenance work such as periodical checks, cleaning, replacement of parts, etc. is required every second or third month. Such maintenance work is costly, and stops the operation of the computer system during the maintenance. As a result, computer operations are often disrupted, thereby down-grading computer reliability.
With the above described dust-proof FA personal computers and FA computers, etc., there is a problem that the powerful fan is noisy, thus degrading the working environment. Besides, a fine filter fills with dust quickly, often reducing fan speed or completely stopping it. Trouble begins as a fan slowdown and leads to a degradation of cooling capability. Finally, heated parts may become badly burned. Therefore, a new device must be designed to prevent these problems. It must detect abnormal rises in the temperature inside a computer system and raise an alarm or forcibly disconnect the power source when the detected temperature exceeds a predetermined value. However, there are some problems with this new device. It is very expensive. Furthermore, when the power source is forcibly disconnected, the whole controlling operation stops and all the .important data being processed is probably lost. This seriously damages the reliability of the computer system.
When a computer system is operated in an undesirable environment, it is recommended that it be sealed in an airtight container. However, there is the problem that a forcible cooling device is not compatible with an airtight structure.